http://www.anandtech.com/show/4475/anandtech-mobile-graphics-guide-summer-2011/4
on the nvidia side you'll probably be looking at a 460m (slightly slower per notebookcheck*), 560m (slightly faster per notebookcheck*), 570m or 580m (there are alot of 15.6" notebook choices with the 460m and 560m)
*i used notebookcheck to compare the 5870m to 460m/560m on several but not all games, thus this might not be entirely accurate
whereas on the ati side you'll probably be looking for a 6870m or 69xxm (most ATI offerings are the mid end 6670m, 6650m, or 5650m)
http://www.notebookcheck.net/ATI-Mobility-Radeon-HD-5870.23073.0.html
newegg filter for high end mobile gaming, <$1600, res >720p
newegg is a good place to search for stuff, since their search works well. They all weigh in excess of 7 lbs though
weight isn't easy to lose for gaming notebooks, all those gaming components are heavy (heatsinks being the primary heat dissipation system doesn't help)
a lot of people fail to account for size in portability

, as the 17" takes up a lot of table space and is bulkier than a 15.6 though
http://www.anandtech.com/show/4496/alienware-m14x-too-much-by-half/1
if you're actually contemplating bringing your notebook to class, I'd just recommend getting an alienware m11x (1366x768

, 4.4lbs) or m14x (1600x900, 6.45lbs). You'll sacrifice a lot of performance with the m11x, some with the 555m (the 555m is about 40% slower than the 5870), but they have decent battery life and are actually pretty portable
at close to 7 hours of battery life, you probably won't even need to bring the charger around which is pretty convenient unless you plan on buying a 2nd charger to carry around (I find it annoying having to pack and unpack the charger daily on my m11x r1, so I just don't bring it [the charger])
the sager 5165 is a nice notebook for the price
the sager has a 15.6" 1920x1080 screen (base), compared to alienware's 14" 1600x900 (optional, 1366x768 base)
the sager uses the slower 144 core 128 bit 555m, compared to alienware's 144 core 192 bit
the sager has a ~4hr battery life (6 cell only), compared to alienware's a ~7hr battery life (8 cell only),